docs: def download_attachments(self, dataset_identifier, content_type="json",
                               download_dir="~/sodapy_downloads"):
          '''
          Download all of the attachments associated with a dataset. Return the paths of downloaded
          files.
          '''
          metadata = self.get_metadata(dataset_identifier, content_type=content_type)
          files = []
          attachments = metadata['metadata'].get("attachments")
          if not attachments:
              logging.info("No attachments were found or downloaded.")
              return files
  
          download_dir = os.path.join(os.path.expanduser(download_dir), dataset_identifier)
          if not os.path.exists(download_dir):
              os.makedirs(download_dir)
  
          for attachment in attachments:
              file_path = os.path.join(download_dir, attachment["filename"])
              has_assetid = attachment.get("assetId", False)
              if has_assetid:
                  base = _format_old_api_request(dataid=dataset_identifier)
                  assetid = attachment["assetId"]
                  resource = "{0}/files/{1}?download=true&filename={2}"\
                             .format(base, assetid, attachment["filename"])
              else:
                  base = "/api/assets"
                  assetid = attachment["blobId"]
                  resource = "{0}/{1}?download=true".format(base, assetid)
  
              uri = "{0}{1}{2}".format(self.uri_prefix, self.domain, resource)
              _download_file(uri, file_path)
              files.append(file_path)
  
          logging.info("The following files were downloaded:\n\t{0}".format("\n\t".join(files)))
          return files